Why Is The Drywall in My Garage Cracking?

Q: Why would long cracks be showing up in the drywall ceiling of our garage for the first time in 12 years?

-BOB B., CARLISLE, PENNSYLVANIA

A: Garages can be surprisingly vulnerable structures. The house gets all the attention, and the garage is where the builder cuts costs. Take fire-taping, for instance. This is the minimalist technique used in garages in which the builder finishes drywall with a single application of tape and drywall compound, helping the structure achieve its fire rating (a measurement of resistance to flame spread) while holding down costs.

Since you're in southeastern Pennsylvania, the scene of record-setting snowfalls last winter, my hunch is that you had snow-load deflection on the garage roof. Smaller rafters or trusses spaced farther apart, a likely cost reduction for a garage roof, can experience more deflection from a heavy snow. This isn't enough to risk collapse, but it can break loose a few drywall joints, especially if they are simply fire-taped.

Repairing the cracks shouldn't be more difficult than driving some drywall screws to ensure that the drywall is properly fastened, then applying paper tape and joint compound over the cracks. Although I think it's unlikely that the trusses (or rafters and joists) were damaged, it couldn't hurt to grab a flashlight and poke around in the attic above the garage. If you find lumber that has cracked or pulled away from truss plates, consult with a licensed architect or structural engineer.

*This article originally appeared in the September 2016 issue of Popular Mechanics.

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